1. Field of the Invention
The present invention relates to a sliding door assembly wherein the sash of the door seals against the door frame.
2. Background of the Prior Art
The main function of a building's envelope is to prevent water penetration into the interior of a building where such water can cause substantial damage. One problem in any envelope design is the junction between two or more items made from dissimilar materials such as where doors and windows integrate with the main building facade. As each item is made from a different material, each such material thermally expands and contracts at a different rate placing stress on the boundary joint of the dissimilar items. Caulks having a high coefficient of expansion and other techniques are used to address this problem. The caulks resiliently expand and contract and help modulate the expansion and contraction of the materials onto which they are deposited upon.
Operable windows are another problem area in building moisture intrusion. By definition, when a window is open, access is provided into the interior of the building. Once the window is closed it must provide a moisture barrier for the building. Windows that swing out to open, similar to doors, press up against a peripheral flange on the window frame, which flange has a gasket thereon, which gasket helps seal the sash of the window against the frame, providing the moisture barrier. In the case of an in-swing door, wherein the bottom of the door does not press up against a sealing flange, appropriate rubber sweeps are placed along the bottom of the door in order to block moisture penetration therepast and the threshold is angled outwardly in order to channel any residual moisture back out.
Sliding windows present another problem in dealing with moisture penetration. As the window must slide up and down in a track, the window cannot press against a sealing flange like a swing window. As the window only presses up against one side of its sash, this is the only side where it is possible to have a press seal against the frame. The opposing side of the window frame, where the sash typically interacts with another sash, which other sash may be fixed or movable, a gasket is provided on one of the sashes in order to provide a barrier between this junction. While such a gasket is not as formidable as a press seal, this junction is constructed such that the upper sash is oriented outwardly relative to the lower sash so that any moisture that challenges this gasket must travel upwardly to get to this seal. While it is possible to have storms that have winds that drive rain upwardly, the vertical vector component of such winds are not very large, therefore, the rain acts on the gasket with only a relatively small force, which the gasket is designed to handle. Additionally, such storms are very infrequent so that the gasket is not subject to frequent substantial challenges.
The sides of the window wherein the sash rides in a track pose a different problem. As the sash must travel up and down along this track, an airtight seal between sash and frame along the track is not possible. However, the tolerances between the sash and the frame are very tight so that most if not all moisture is stopped at the junction of sash and frame. For any moisture that bypasses this junction, the frames typically have a flanging system that deflects the water and channels the water back to the outside.
The problems associated with moisture barrier protection for horizontal sliding sashes and more particularly sliding glass doors is much more challenging. The junction between two closed sashes on a sliding glass door is vertically oriented. Therefore, the gasket that seals the junction between the two sashes is subject to rain any time the wind blows from the appropriate direction during a storm and as the door is at ground level, the lower part of the junction is subject to a rain load almost every shower due to the rain hitting the ground proximate the sash and splashing against the seal. Additionally, the flanging systems used on the windows to deflect moisture that passes the sash-frame contact area cannot be effectively used on the lower part of the door. As people must be able to pass through the door, the lower threshold must be kept to a reasonably short height in order to adequately facilitate walking therethrough. This height restriction is set not only by the desired comfort level of users of the door, but also by the Americans with Disabilities Act which sets upper height restrictions on all new construction sliding doors. Therefore, vertically disposed flanging systems that are commonly found on hung windows, which systems tend to be relatively wide, cannot be effectively deployed on a sliding glass door that has threshold height restrictions and that also requires that the threshold be subject to the load forces associated with people walking thereon. Accordingly, moisture barrier systems found on sliding doors tend to be less reliable relative to other door and window moisture barrier systems.
The flanging systems found on current sliding doors tend to have multiple spaced apart flanges in order to accommodate the tracks upon which each sash of the door slides and to act as rain barriers. Such a multiple flange configuration, even though it is relatively low in height, is somewhat uncomfortable to walk across and is difficult to bypass in a wheelchair that must pass across the several flanges.
Additionally, sliding doors tend to be larger relative to most windows, therefore, they tend to become “loose” over time through repeated use. As such doors require tight interfitting parts in order to achieve a strong moisture barrier capability, such loosening tends to degrade the moisture barrier capabilities of the door.
My previous patent, U.S. Pat. No. 6,826,867, incorporated herein in its entirety by reference, provides a sliding door system that has moisture barrier capabilities that address the above stated problems found in the art. While the sliding door assembly disclosed in my previous patent works with a high degree of efficiency and reliability, I have made several improvements that further enhance the capabilities and effectiveness of the sliding door assembly, which improvements are the subject of the present patent.